Cadmium tolerant microbial strains possess different mechanisms for cadmium biosorption and immobilization in rice seedlings. (September 2022)

• Record Type: Journal Article
• Authors: Ali, Qurban; Ayaz, Muhammad; Yu, Chenjie; Wang, Yujie; Gu, Qin; Wu, Huijun; Gao, Xuewen
• Is Part Of: Chemosphere. Volume 303:Part 3(2022)
• Publication Date: 2022-09
• Subjects: Bacillus sp. heavy metals -- Rice -- Microbial biosorption -- Kinetic models; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.135206
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Heavy metal remediation, such as cadmium (Cd 2+ ) by microbial strains is efficient and environment-friendly. In this current study, we exploited the potential of Bacillus strains (Cd 2+ -tolerant; NMTD17, GBSW22, and LLTC96) to regulate Cd 2+ biosorption mechanisms and improve rice seedling growth. The results showed that initial concentration and contact time affected Cd 2+ biosorption, and the kinetic models of pseudo orders were effective in the elaborate biosorption process. Mainly, the bacterial cell wall had the potential for Cd 2+ biosorption, and we found non-significant biosorption alterations among bacterial strains' inner and outer surfaces of cell membranes. Furthermore, the Fourier transform infrared (FTIR) spectroscopy analysis identified the differences in functional groups, such as C–N, PO2, –SO3, CO, COOH, C–O, C–N, –OH, and –NH that interact in biosorption by Bacillus strains. The scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) examination revealed that the binding of Cd 2+ to microbes was mostly based on ion exchange pathways. Moreover, the Bacillus strains responded to Cd 2+ stress in rice under pot experiment at various concentrations (0, 0.25, and 0.50 mg kg −1 ), and they also influenced the chlorophyll contents and antioxidants activities were studied. The analysis of physio-morphological parameters was observed to be increased, which indicated that all Bacillus strains showed significant effects on rice growth under Cd 2+ stress. These results revealed that the selected strains had the capability for additional use in the development of Cd 2+ bioremediation methods. These strains also provided plant growth-promoting (PGP) traits that can alleviate the harmful effects of Cd 2+ in rice plants. Graphical abstract: Image 1 Highlights: Bacillus sp. increased adsorption of Cd 2+ on the cell wall. Lterations in functional groups that were involved in Bacillus -Cd 2+ biosorption. Bacillus microbial strains increased Cd 2+ immobilization in soil. Microbial strains reduced Cd 2+ content and improved plant growth. Suitable microbial species that may be modified to enhance Cd 2+ biosorption.